In order to cope with tremendously growing wireless data traffic in recent years, wireless operators and equipment manufacturers have been exploring different options to address high traffic areas with more bandwidth. One attractive option is adapting Long Term Evolution (LTE) to operate in an unlicensed frequency band or spectrum. This option combines the robust operation benefits of LTE with the large amount of bandwidth available in unlicensed spectrum. Furthermore, such an adapted LTE network can be controlled by one core network and thus requires low operational expenses. However, other existing wireless technologies (e.g., WiFi) already operate in unlicensed frequency bands. It is therefore necessary to devise coexistence solutions to ensure fair sharing among LTE and other wireless technologies in an unlicensed frequency band. As such, new LTE standards are being developed to make use of unlicensed shared spectrum. Some of these technologies are termed as LTE Unlicensed (LTE-U), Licensed Access LTE (LA-LTE), or Licensed Assisted Access LTE (LAA-LTE).
There are a number of technical issues that must be addressed in order to deploy LTE in shared unlicensed spectrum. Shared unlicensed spectrum operates very differently compared to traditional licensed 3rd Generation Partnership Program (3GPP) spectrum. Users of unlicensed spectrum must share the spectrum resources with other wireless, or radio, technologies, and do so in a fair way while at the same time ensuring that the spectrum is used as efficiently as possible. In addition, many different wireless technologies may use unlicensed spectrum, e.g., WiFi. By contrast, the LTE protocols and specifications have been developed on the premise that only LTE nodes operate in the same spectrum.
One of the most significant current aspects for LTE-U is the requirement that the LTE-U enhanced, or evolved, Node B (eNB) periodically stops all transmissions in order to allow other technologies to access the radio channel. This ON/OFF transmission is in the order of tens to hundreds of milliseconds (ms) and can be dynamically changed based on radio channel usage.
In light of the discussion above, there is a need for systems and methods that enable coexistence of LTE and one or more other wireless technologies in the same shared unlicensed spectrum.